Operating members of this type are used in many different application fields, for example, as a manual operation terminal.
Such operating members are distinguished mainly by the possibilities of an optionally right-handed or left-handed operation. For this purpose, one key button respectively is provided on the mutually opposite sides to switch a unit on and off and is connected to the operating member.
In addition to the requirement of having an emergency off push button, it is also necessary to design the key button such that the switch is switched-off when panic-caused reflex-type continued pressing takes place onto the key button.
In this case, the key button is pressed down and held for the purpose of a switch-on, and it rebounds into a switch-off position when it is released. In the event of a panic reaction and the above-mentioned continued unintentional further depression of the key button, a switch-off should, however, also take place.
In order to permit this sequence, a high-cost electronic system has been used, particularly since it has to be possible to implement the above-mentioned switchings of both key buttons independently of one another.
The electronic system required so far naturally results in considerable manufacturing costs which are found to be disadvantageous since the concerned operating members are used in large quantities.
However, with respect to the operation, the electronic components are also interference-prone. They also require special constructive protection measures, that is, casing measures in order to protect them from the occasionally rough operation in which such operating members are used.
It is therefore an object of the present invention to further develop an operating member of the above-mentioned type such that it has a simple construction, can therefore be produced in a cost-effective manner and is operationally robust.
This operating member is an extremely simple construction with respect to its switching-on because an electronic system can be completely eliminated.
The exclusively mechanical switching device can be produced and mounted in a simple manner. Furthermore, it is a robust construction which results in a low susceptibility to interferences and in a long service life.
According to an advantageous further development of the invention, the switch can be operated by two mutually independently operating switching elements. Each switching element is connected with one of the two key buttons.
This independence of the switching elements permits an equally independent operation of the key buttons on the right or the left side.
The switch may be arranged in a central manner, in which case the key buttons and the switching elements fastened thereto are mounted mirror image or symmetrically.
In principle, the electrical switch, operating as a safety switching device, may be arranged in a housing on whose exterior side recessed grips are fastened which carry the key buttons. The switching elements may be movable by an operating linkage.
In its operating sequence, the switch is conceived such that, after the operation of the panic switching device, during the subsequent restoring into the switched-off position, it skips over the switched-on position.
It is also conceivable to release the switch from the panic position by a separate unlocking, preferably a manual unlocking, also by skipping the switched-on position.
Depending on the space requirements, the switch may also be mounted in a decentralized manner with respect to the key buttons in a housing. In this case, respectively suitable driving elements are to be provided by which the key buttons can be brought into an operative connection with the switch.
In addition to taking place by means of the above-mentioned switching elements, the operation of the switch may also take place by curves, connecting links or the like whose construction, like that of the switching elements, depends on the constructional conditions and in each case has to be individually conceived.
These and other aspects of the present invention will become apparent from the following detailed description of the invention, when considered in conjunction with accompanying drawings.